Featured Research

from universities, journals, and other organizations

Bacteria: Chemists monitor single-molecule switching in action

Date:

May 2, 2011

Source:

Österreichisches Genomforschungsprogramm GEN-AU

Summary:

In various ways, bacteria are one step ahead to us humans. For example, they dispose of "intelligent" RNA molecules, so-called riboswitches, which help to regulate many of their essential metabolism pathways. The riboswitches, only discovered a few years ago, are sensors in RNA molecules. A riboswitch acts similarly to a motion sensor that switches on or off the light when people are nearby: the riboswitch switches genes off or on when certain metabolism products are present in a cell. There is no similar mechanism of gene regulation in humans, therefore this represents an ideal target for new antibiotics.

Share This

In various ways, bacteria are one step ahead to us humans. For example, they dispose of "intelligent" RNA molecules, so-called riboswitches, which help to regulate many of their essential metabolism pathways. The riboswitches, only discovered a few years ago, are sensors in RNA molecules. A riboswitch acts similarly to a motion sensor that switches on or off the light when people are nearby: the riboswitch switches genes off or on when certain metabolism products are present in a cell. There is no similar mechanism of gene regulation in humans, therefore this represents an ideal target for new antibiotics.

Related Articles

However, how the sensoring and switching process is transduced has remained widely unexplained since the discovery of riboswitches. Now, an international team under the leadership of chemists from Innsbruck succeeded in monitoring the S-adenosylmethionine (SAM) II-riboswitch in action. SAM is a cofactor which is involved in many metabolism processes by transferring methyl groups to other molecules.

Molecules are twitchy

The scientists Andrea Haller and Ronald Micura from the Institute of Organic Chemistry and the Center for Molecular Biosciences of the University of Innsbruck, together with Scott Blanchard from the Weill Cornell Medical College in New York, recorded the movements of single riboswitch molecules by using a technique called smFRET (single-molecule Fluorescence Resonance Energy Transfer). This was reported by the journal Nature Chemical Biology. The scientists discovered that SAM II-riboswitches are extremely "twitchy" molecules, undergoing immensely fast structure changes. "The key to understanding their function lies just in these dynamics," Micura explains. His team's work was done in line with the GEN-AU project for non-coding RNAs which is managed by Innsbruck's company CEMIT (for more information see below) and also supported by the Austrian Science Fund FWF.

The switching is constantly simulated

The SAM II-riboswitch switches off when a SAM molecule binds to it. Then it forms a structure where the genetic information is not accessible any more. By means of the smFRET technique and other methods, Micura's team was able to analyze for the first time in detail what is happening at the time of the binding event. As expected, they noticed that the free riboswitch has an open structure at first, where the genetic information is easily accessible. However, the riboswitch simulates constantly the switching action even when there is no SAM molecule nearby. The riboswitch is swinging back and forth in microseconds time scale between the open structure and a state which resembles the off-state. When a SAM molecule appears, it binds to the "nearly-off-state," a minimal change in structure occurs, and the switch is finally turned off. Hence, the structure becomes fixed.

Single molecules establish a new dimension for research

Micura and his team are thrilled about this discovery. Just now, in the International Year of Chemistry 2011, it becomes more apparent that this is far from a disenchanted science whose mysteries are unraveled. On the contrary: knowledge was used to rely mostly on mean data which were measured in a great number of molecules simultaneously. Today it is technically feasible to monitor single molecules and observe their individual behavior. "This is a completely new dimension for research and extremely exciting," says Micura.

Background on riboswitches

Riboswitches are found in the messenger RNA (mRNA) which transports the genetic code for proteins. They themselves do not code for a protein sequence. Riboswitches function by blocking the mRNA when their target molecule is binding. Then the genetic information cannot be used any further. In most cases, this represents the gene which is responsible for the synthesis of the target molecule. A feedback reaction takes place: if the concentration of the target molecule is too high, its production will be stopped.

More From ScienceDaily

More Plants & Animals News

Featured Research

Mar. 3, 2015 — While studying a ground-nesting bird population near El Reno, Okla., a research team found that stress during a severe weather outbreak of May 31, 2013, had manifested itself into malformations in ... full story

Mar. 3, 2015 — The 3-D printing scene, a growing favorite of do-it-yourselfers, has spread to the study of plasma physics. With a series of experiments, researchers have found that 3-D printers can be an important ... full story

Mar. 3, 2015 — Most people consume more salt than they need and therefore have a higher risk of heart disease and stroke, which are the two leading causes of death worldwide. But a new study reveals that dietary ... full story

Mar. 3, 2015 — By examining the forces that the segments of mosquito legs generate against a water surface, researchers have unraveled the mechanical logic that allows the mosquitoes to walk on water, which may ... full story

Mar. 3, 2015 — Pediatric otolaryngologists and surgeons are concerned with parents getting the wrong message regarding the safety/desirability of letting babies and young children eat peanuts to prevent them from ... full story

Mar. 3, 2015 — Researchers have developed a new way of rapidly screening yeasts that could help produce more sustainable biofuels. The new technique could also be a boon in the search for new ways of deriving ... full story

Mar. 3, 2015 — Similar to humans and animals, plants possess an innate immune system that protects them from invading pathogens. Molecular structures that only occur in pathogens enable their recognition and ... full story

Mar. 3, 2015 — For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth's oceans: Why does calcium carbonate, the tough material of seashells and corals, ... full story

Mar. 3, 2015 — To simulate chimp behavior, scientists created a computer model based on equations normally used to describe the movement of atoms and molecules in a confined space. An interdisciplinary research ... full story

Featured Videos

Rare Goblin Shark Found in Australia

AFP (Mar. 3, 2015) — A goblin shark, a rare sea creature described as an &apos;alien of the deep&apos; is found off Australia and delivered to the Australian Museum in Sydney. Duration: 01:25
Video provided by AFP

Zookeepers Copy Animal Poses In Hilarious Viral Photos

Buzz60 (Mar. 2, 2015) — Zookeepers at the Symbio Wildlife Park in Helensburgh, Australia decided to take some of their favorite animal photos and recreate them by posing just like the animals. Jen Markham (@jenmarkham) has the story.
Video provided by Buzz60

Related Stories

Nov. 4, 2013 — Riboswitches are RNA segments that switch genes on and off, either during DNA transcription or during protein translation, but little is known about the precise workings of this process. A new study ... full story

Oct. 21, 2012 — Biochemists have discovered a genetic sequence that can alter its host gene's activity in response to cellular energy levels. The scientists have found this particular energy-sensing switch in ... full story

Mar. 30, 2010 — The organelles of photosynthesis -- the chloroplasts -- have their own DNA, messenger RNA and ribosomes for forming proteins. Scientists have now discovered how to regulate the formation of proteins ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.